Abstract
[Background] Practice effect refers to the improvement in performance after repeatedly performing a task. The computations underlying practice effects and whether their magnitude varies around the visual field are unknown. Here, we used a detection task and reverse correlation to ask (1) whether task performance and representation for orientations and spatial frequencies (SF) change with practice, (2) what is the association between task performance and representation changes and (3) do task performance and featural representation interact with visual field location. [Method] Observers detected a horizontal Gabor embedded in noise appearing at either the fovea or four locations at 6° eccentricity: left/right horizontal meridian (HM) and upper/lower vertical meridian (VM). We calculated contrast sensitivity by taking the reciprocal of the Gabor contrast titrated per location. At each location, we grouped the data into 4 separate bins (containing ~600 subsequent trials) and implemented reverse correlation in each to estimate the weights assigned by the visual system to a range of orientations and SFs, interpreted as the perceptual sensitivity to the corresponding feature. We then characterized and compared these representations across bins and locations. [Results] Over practice: (1) Contrast sensitivity increased at all locations, confirming that performance improved. Meanwhile, the perceptual sensitivity to task-relevant orientations (except at the lower VM) and SF (except along the VM) increased; (2) Contrast sensitivity increased proportionally with greater sensitivity to task-relevant orientations, suggesting that the increased perceptual sensitivity to task-relevant orientations underlies the observed practice effect; (3) the extent of increment in the contrast sensitivity and changes in tuning characteristics were similar across locations. [Conclusion] These data indicate that practice improves detection performance and modulates the representation of features similarly around the visual field. The change in the feature representation, especially the increased sensitivity to task-relevant orientations, may underlie improved performance.